Comcast WGR614 Port forwarding issue?

this may be stupid but some routers have this stupid java script that checks the ip address on the event that you remove focus from the text box. Then the pop up box says invalid ip, so say if i type 192.168 and i decide to click on something else, it reads it as an error, either putting in the whole ip or removing it completely works. Also check there are no weird characters and that you have periods and not comma's and silly things like that. =)